CN113008979A - Method for determining the concentration of a liquid - Google Patents

Method for determining the concentration of a liquid Download PDF

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Publication number
CN113008979A
CN113008979A CN202011506675.5A CN202011506675A CN113008979A CN 113008979 A CN113008979 A CN 113008979A CN 202011506675 A CN202011506675 A CN 202011506675A CN 113008979 A CN113008979 A CN 113008979A
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China
Prior art keywords
ultrasonic
propagation time
ultrasound
reflecting surface
ultrasonic transducer
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Pending
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CN202011506675.5A
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Chinese (zh)
Inventor
J·M·霍夫曼
R·维因曼
T·冈萨雷斯-巴奎特
T·赫夫肯
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of CN113008979A publication Critical patent/CN113008979A/en
Pending legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/222—Constructional or flow details for analysing fluids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/024—Analysing fluids by measuring propagation velocity or propagation time of acoustic waves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
    • G01H3/04—Frequency
    • G01H3/08—Analysing frequencies present in complex vibrations, e.g. comparing harmonics present
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H5/00—Measuring propagation velocity of ultrasonic, sonic or infrasonic waves, e.g. of pressure waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/341—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with time characteristics
    • G01N29/343—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with time characteristics pulse waves, e.g. particular sequence of pulses, bursts
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/42—Detecting the response signal, e.g. electronic circuits specially adapted therefor by frequency filtering or by tuning to resonant frequency
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/05—Systems for adding substances into exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/12—Other sensor principles, e.g. using electro conductivity of substrate or radio frequency
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
    • F01N2900/1806—Properties of reducing agent or dosing system
    • F01N2900/1818—Concentration of the reducing agent
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/022—Liquids
    • G01N2291/0228—Aqueous liquids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0258—Structural degradation, e.g. fatigue of composites, ageing of oils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/045—External reflections, e.g. on reflectors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Pathology (AREA)
  • Immunology (AREA)
  • General Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Acoustics & Sound (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Toxicology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

Method for determining the concentration of a liquid. The invention relates to a method for determining the concentration of a liquid (3), wherein an ultrasonic transducer (72) and at least two ultrasound-reflecting surfaces (731, 732) which are at different distances from the ultrasonic transducer (72) are arranged on a carrier element (73) which is designed in one piece. The concentration is determined during a measurement operation from a first propagation time of the ultrasonic signal between the ultrasonic transducer (72) and the first ultrasonic reflection surface (731) without the ultrasonic signal being reflected at the other ultrasonic reflection surface (732). In a calibration operation, a first propagation time and a second propagation time (93, 94) of the ultrasonic signal between the first ultrasonic reflection surface (731) and at least one further ultrasonic reflection surface (732) are determined.

Description

Method for determining the concentration of a liquid
Technical Field
The invention relates to a method for determining the concentration of a liquid. The invention also relates to a computer program for carrying out each step of the method and to a machine-readable storage medium on which the computer program is stored. Finally, the invention relates to an electronic control device designed to implement the method.
Background
In order to reduce the proportion of nitrogen oxides in the exhaust gas of internal combustion engines, in particular diesel engines, it is known to arrange an SCR (Selective Catalytic Reduction) Catalytic converter (katalyzer) in the exhaust gas line of said internal combustion engines, in particular diesel engines. The SCR catalytic converter reduces nitrogen oxides contained in the exhaust gas in the presence of ammonia as a nitrogen reducing agent. In order to provide ammonia, a reducing agent solution is injected into the exhaust gas line upstream of the SCR catalytic converter. For this purpose, aqueous urea solutions (urea-water solutions; HWL) are generally used, which contain urea as ammonia decomposition agent. HWL of 32.5% is commercially available under the name AdBlue @.
The emission protection law requires that the quality, i.e. the concentration of the HWL used, be monitored by means of a quality sensor in order to detect possible misfuelling, in particular by the vehicle driver. The mis-refuelling may be performed, for example, with water or with a diluted HWL. When such a faulty refuelling is recognized, the driver is warned and finally the operation of the vehicle is restricted with a so-called "incentive" (induction). The mass sensor may have an ultrasonic transducer or an ultrasonic reflecting surface, so that the concentration of the HWL can be calculated from the propagation time of the ultrasonic signal between the ultrasonic transducer and the ultrasonic reflecting surface. For this purpose, the distance between the ultrasonic transducer and the ultrasonic reflection surface must be known. In this regard, such mass sensors are calibrated by the manufacturer in order to eliminate unavoidable manufacturing effects. However, the subsequent mounting process can lead to changes in the measurement path and thus to a deterioration in the measurement accuracy.
DE 102018202587 a1 proposes arranging a plurality of ultrasound reflection surfaces on a carrier element which is of a common, integral design. The ultrasonic signals emitted by the ultrasonic transducers are thereby reflected with different propagation times in the measuring operation, which enables the measurement to be carried out by means of the differential measurement principle.
Disclosure of Invention
In a method for determining the concentration of a liquid, in particular HWL, in particular stored in a tank, for example a reducing agent tank, it is provided that an ultrasonic transducer and at least two ultrasonic reflection surfaces, in particular exactly two ultrasonic reflection surfaces, are provided. The ultrasound reflection surfaces are arranged at different distances from the ultrasound transducer at a carrier element of a common integral design, wherein the carrier element is arranged in particular in the tank. The ultrasonic transducer and the ultrasonic reflection surface together form a mass sensor for determining the concentration of the liquid. The mass sensor operates in the method with measurement and with calibration material:
in the measuring operation, the concentration is determined from a first propagation time of the ultrasonic signal between the ultrasonic sensor and the first ultrasonic reflection surface. In this case, no reflection of the ultrasonic signal at the other ultrasonic reflection surface occurs. This measuring operation, in which only the propagation time of the ultrasonic signal is evaluated, is less computationally intensive and can be carried out in a similar manner to the measuring operation of a mass sensor, which has only one ultrasonic reflection surface in addition to its ultrasonic transducers.
In a calibration operation, a second propagation time of the ultrasonic signal between the first ultrasonic-wave reflecting surface and at least one other ultrasonic-wave reflecting surface is determined. For the determination of the concentration during the measurement operation, the measurement distance between the ultrasonic transducer and the first ultrasonic reflection surface needs to be known. If the ultrasonic transducer and the carrier element are mounted together on a plastic surface, for example on the surface of a transport module for liquids, the measuring section can deviate from the initial calibration due to the post-mounting process in the tank. Instead, the distance of the ultrasound-reflecting surfaces from each other is defined by the carrier element. These ultrasonic reflecting surfaces can thus be used for calibration used in the measurement operation.
In order to calculate the second propagation time, a third propagation time of the ultrasonic signal between the ultrasonic transducer and the further ultrasonic reflection surface is preferably determined as a basis for determining the first propagation time. The ultrasonic signal is reflected at least once at least one other ultrasonic reflection surface. Additionally, a first propagation time is also determined. The second propagation time is then calculated as the difference between the third propagation time and the first propagation time. In the case of this difference calculation, the influence of the spacing between the ultrasonic transducer and the ultrasonic wave reflecting surface is eliminated.
In a particularly preferred embodiment, the further ultrasound-reflecting surface is the first ultrasound-reflecting surface, at which the ultrasound signal is reflected on the path between the ultrasound transducer and the further ultrasound-reflecting surface, when the third propagation time is measured. In this way, it is sufficient to carry out the method if only two ultrasound-reflecting surfaces are formed on the carrier element.
The distance between the ultrasonic transducer and the first ultrasonic reflection surface is preferably determined in a calibration operation by the ratio between the second propagation time and the first propagation time. The ratio of the distance to be determined of the ultrasonic signals between the ultrasonic reflection surfaces to the known propagation path (which is predefined by the geometry of the carrier element) corresponds to the ratio of the second propagation time to the first propagation time.
Preferably, the calibration operation is performed when the ultrasonic transducer is first turned on. This makes it possible to dispense with calibration on the production side. Even when a calibration on the production side should be present, the calibration operation when the ultrasound transducer is first switched on makes it possible to compensate for deviations in the distance between the ultrasound transducer and the first ultrasound reflection surface, which occur after the calibration on the production side as a result of a subsequent mounting process.
If the tank is a reducing agent tank of an SCR catalytic converter system of a motor vehicle, it is also preferred that a calibration operation is carried out in a predefined driving state of the motor vehicle. The driving state can be predefined in such a way that the most favorable measuring conditions are present in the case of the driving state. In this case, a uniform temperature distribution (small temperature gradients) or a stable driving situation (constant speed) can be involved, in particular.
In the measuring operation and in the calibration operation, the ultrasonic transducer preferably emits a transient pulse signal in a frequency range between 0.5MHz and 10.0 MHz. Particularly preferably, the transient pulse signal is between 1.0MHz and 2.0 MHz. This frequency range allows good spatial focusing of the ultrasonic field and an accurate determination of the transit time without unacceptably high absorption of the acoustic energy in the liquid occurring here.
The computer program is set up to carry out each step of the method, in particular when the computer program runs on a computing device or an electronic control device. The computer program enables different embodiments of the method to be implemented on an electronic control device without structural changes being necessary to this. For this purpose, the computer program is stored on a machine-readable storage medium.
By loading the computer program onto a conventional electronic control device, an electronic control device is obtained which is set up for determining the concentration of the liquid by means of the method.
Drawings
Embodiments of the invention are illustrated in the drawings and are further set forth in the description that follows.
Fig. 1 shows a schematic representation of a reducing agent tank in which a liquid is stored, the concentration of which can be determined by means of an embodiment of the method according to the invention.
Fig. 2 shows a schematic top view of a mass sensor arranged in the reducing agent tank according to fig. 1.
Fig. 3 shows a propagation path of an ultrasonic signal in the mass sensor according to fig. 2 in an embodiment of the method according to the invention.
Fig. 4 shows a further propagation path of an ultrasonic signal in the mass sensor according to fig. 2 in an embodiment of the method according to the invention.
Fig. 5 shows a flow chart of an embodiment of the method according to the invention.
Detailed Description
Fig. 1 shows elements of an SCR catalytic converter system 1 of a motor vehicle, which are not shown. The SCR catalytic converter system has a reducing agent tank 2. A liquid 3 is stored in the reducing agent tank 2, the liquid 3 being HWL. The extraction module 4 is arranged at the bottom of the reductant tank 2. The extraction module carries a delivery device 5, by means of which delivery device 5 liquid 3 can be drawn off from the reducing agent tank 2 and can be transported to the metering valve of the SCR catalytic converter system 1 by means of a line 6. In order to determine the concentration of the liquid 3, a mass sensor 7 is arranged on the extraction module 4, which is controlled by an electronic control device 8.
As shown in fig. 2, the mass sensor 7 has a base 71, which in the present example consists of HDPE (High Density Polyethylene). On the bottom, an ultrasonic transducer 72 is arranged. Furthermore, in the present exemplary embodiment, a carrier element 73 made of stainless steel is arranged on the base 71, which carrier element carries the two ultrasound-reflecting surfaces 731, 732. The first ultrasonic reflection surface 731 is arranged at a distance d from the ultrasonic transducer 72. The first ultrasonic reflection surface 731 is located opposite to the ultrasonic transducer 72 such that the first ultrasonic reflection surface 731 reflects an ultrasonic signal emitted from the ultrasonic transducer 72 back to the ultrasonic transducer 72 and also reflects the ultrasonic signal to the second ultrasonic reflection surface 732. The second ultrasonic reflection surface 732 is arranged such that the ultrasonic signal emitted by the ultrasonic transducer 72 cannot impinge on the second ultrasonic reflection surface 732 without previous reflection.
The ultrasonic transducer 72 generates a momentary pulse signal with a frequency of 1.0MHz in the present embodiment by means of a piezoelectric crystal. If a signal is emitted from the output point 721 of the ultrasonic transducer 72, the signal is incident on the first ultrasonic reflection surface 731. As shown in fig. 3, a portion of the signal is reflected back to the output point 721 and is received there by the piezoelectric crystal.
Fig. 4 shows that another part of the signal is reflected from the first ultrasonic reflection surface 731 onto the second ultrasonic reflection surface 732. The ultrasonic signal is reflected from the second ultrasonic reflecting surface 732 back onto the first ultrasonic reflecting surface 731, and the first ultrasonic reflecting surface 731 reflects the ultrasonic signal on to the ultrasonic transducer 72 where it is received by the piezoelectric crystal at the incident point 722. The two echoes can be distinguished from each other by different propagation times.
Fig. 5 shows that, after the start 90 of an embodiment of the method according to the invention, a first check 91 is first made: whether there is a first activation of ultrasonic transducer 72. If the condition is satisfied, a calibration operation is performed. If there is no first actuation, a second check 92 is made: whether a driving state of the motor vehicle exists, which makes a calibration operation necessary. If this condition is met, the calibration operation is started as well. In this calibration operation, an ultrasonic signal is emitted by the ultrasonic transducer 72. First, a first propagation time of the ultrasonic signal between the ultrasonic transducer 72 and the first ultrasonic reflection surface 731 according to fig. 3 is determined 93. After the first echo of the ultrasonic signal has been analyzed in this way, a second propagation time of the ultrasonic signal on the path according to fig. 4 is determined 94. The travel time of the ultrasonic signal between the two ultrasonic reflection surfaces 731, 732 is then calculated 95. For this purpose, a difference between the second propagation time and the first propagation time is formed. To determine 96 the distance between ultrasonic transducer 72 and first ultrasonic reflection surface 731, the third propagation time and the first propagation time are proportional to each other. This ratio corresponds to the ratio between the distance d between the ultrasonic transducer 72 and the first ultrasonic reflection surface 731 to the distance between the two ultrasonic reflection surfaces 731, 732. Calibration 97 of the mass sensor 7 is performed with the distance d now known. The method is then switched into a measuring operation 98. If the necessity of a calibration operation is not determined in either of the two checks 91, 92, the measurement operation is immediately started.
In a measuring operation, the ultrasonic transducers 72 emit ultrasonic signals and each analyze only the first echo of the ultrasonic signals in accordance with the measuring section in fig. 3. Only the first propagation time of the ultrasonic signal is therefore available, from which the concentration of urea in the liquid 3 is calculated using the now known distance d. When the concentration is lower than the threshold value, incentive (Inducement) of the vehicle is executed.

Claims (10)

1. Method for determining a concentration of a liquid (3), wherein an ultrasonic transducer (72) and at least two ultrasound-reflecting surfaces (731, 732) are arranged on a carrier element (73) which is designed in one piece, wherein the at least two ultrasound-reflecting surfaces (731, 732) are at different distances from the ultrasonic transducer (72), characterized in that the concentration is determined from a first propagation time of an ultrasonic signal between the ultrasonic transducer (72) and a first ultrasound-reflecting surface (731) without the ultrasonic signal being reflected at the other ultrasound-reflecting surface (732) in a measuring operation, and in that a second propagation time (93, 94) of the ultrasonic signal between the first ultrasound-reflecting surface (731) and at least one other ultrasound-reflecting surface (732) is determined in a calibration operation.
2. Method according to claim 1, characterized in that the second propagation time is calculated by determining a third propagation time of the ultrasonic signal between the ultrasonic transducer (72) and another ultrasonic reflecting surface, wherein at least one reflection of the ultrasonic signal at least one other ultrasonic reflecting surface takes place, and calculating the difference (95) between the third propagation time and the first propagation time.
3. The method of claim 2, wherein the other ultrasound reflecting surface is the first ultrasound reflecting surface (731) when the third travel time is measured.
4. A method according to any one of claims 1 to 3, characterized in that the distance (96) between the ultrasonic transducer (72) and the first ultrasonic-wave reflecting surface is determined from the ratio between the second propagation time and the first propagation time in a calibration operation.
5. Method according to any one of claims 1 to 4, characterized in that the calibration operation is performed when the ultrasonic transducer (72) is first switched on.
6. A method according to any one of claims 1 to 5, characterised in that a carrier element (73) is arranged in a reducing agent tank (2) of an SCR catalytic converter system (1) of a motor vehicle and a calibration operation is carried out in a predefined driving state of the motor vehicle.
7. Method according to any one of claims 1 to 6, characterized in that the ultrasonic transducer (72) emits a momentary pulse signal in a frequency range between 0.5MHz and 10.0MHz in the measuring operation and in the calibration operation.
8. Computer program set up to perform each step of the method according to any one of claims 1 to 7.
9. A machine-readable storage medium on which the computer program according to claim 8 is stored.
10. Electronic control device (8) which is set up for determining the concentration of the liquid (3) by means of the method according to one of claims 1 to 7.
CN202011506675.5A 2019-12-20 2020-12-18 Method for determining the concentration of a liquid Pending CN113008979A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102019220344.2A DE102019220344A1 (en) 2019-12-20 2019-12-20 Method for determining a concentration of a liquid
DE102019220344.2 2019-12-20

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CN113008979A true CN113008979A (en) 2021-06-22

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DE (1) DE102019220344A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102023203819A1 (en) 2023-04-25 2024-10-31 Continental Automotive Technologies GmbH supply module for a cleaning system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202013006909U1 (en) * 2013-07-31 2014-08-04 Seuffer Gmbh & Co.Kg Sensor device for detecting properties of fluid media
DE102014213233A1 (en) * 2014-07-08 2016-01-14 Continental Automotive Gmbh Device for determining a speed of sound of a sound signal in a fluid
DE102014109843A1 (en) * 2014-07-14 2016-01-14 Continental Automotive Gmbh Method for determining the level in a tank
DE102018202587A1 (en) * 2018-02-21 2019-08-22 Robert Bosch Gmbh Device for determining quality, tank device

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